Improved methods for enterovirus inactivation, adjuvant adsorption and dose reduced vaccine compositions obtained thereof

ABSTRACT

The present invention is directed to improved methods of Enterovirus inactivation by formaldehyde in presence of tromethamine buffer resulting in maximum recovery of D-antigen. Subsequent adsorption of said sIPV on aluminium hydroxide provides significantly dose reduced sIPV compositions.

BACKGROUND OF THE INVENTION

The prevalence of polio virus has largely been decreased by the use ofOral Polio Vaccine (OPV), based on live-attenuated Sabin polio strains.However, OPV has limitations for the post-eradication era. Therefore,development of Sabin-IPV plays an important role in the WHO polioeradication strategy. The use of attenuated Sabin instead of wild-typeSalk polio strains will provide additional safety during vaccineproduction. Moreover, to prevent the emergence of circulatingvaccine-derived polioviruses (cVDPVs), the use of OPV should bediscontinued following polio eradication, and replaced by IPV. ThesecVDPVs are transmissible and can become neurovirulent (similar to wildpolioviruses) resulting in vaccine associated paralytic poliomyelitis.Such strains can potentially re-seed the world with polioviruses andnegate the eradication accomplishments.

IPV is delivered by intramuscular (IM) or deep subcutaneous (SC)injection. IPV is currently available either as a non-adjuvantedstand-alone formulation, or in various combinations, including DT-IPV(with diphtheria and tetanus toxoids) and hexavalentDTPHepB-Hib-IPVvaccines (additionally with pertussis, hepatitis B, and Haemophilusinfluenzae b. The currently acceptable standard dose of polio vaccinescontains D antigens as 40 Units of inactivated poliovirus type 1(Mahoney), 8 units of inactivated poliovirus type 2 (MEF-I) and 32 unitsof inactivated poliovirus type 3 (Saukett) (e.g. Infanrix-IPV™).Existing preparations of stand-alone IPV do not contain adjuvant.

Most experts agree that worldwide use of IPV is preferable because ofits proven protective track-record and safety. However, when compared toOPV, the cost-prize for IPV is significantly higher. This is mainly dueto requirements for: (i) more virus per dose; (ii) additional downstreamprocessing (i.e. concentration, purification and inactivation), and therelated QC-testing (iii) loss of antigen or poor recovery in downstreamand iv) containment. Until now, the financial challenge has been a majordrawback for IPV innovation and implementation in low and middle-incomecountries. The production costs of sIPV are currently estimatedequivalent to that for IPV, which is about 20-fold more expensive thanOPV. The future global demand for IPV following eradication ofpolioviruses could increase from the current level of 80 million dosesto 450 million doses per year. Consequently, approaches to “stretch”supplies of IPV are likely to be required.

Reduced-dose efficacious vaccine formulations which provide protectionagainst infection using a lower dose of IPV antigen are desirable insituations where the supply of conventional vaccine is insufficient tomeet global needs or where the cost of manufacture of the conventionalvaccine prevents the vaccine being sold at a price which is affordablefor developing countries. Also the exposure to lower dose of IPV;compared to the existing marketed formulations could be more safer.Thus, various strategies to make IPV available at more affordable pricesneed to be evaluated.

In case of pandemic influenza vaccines the use of adjuvants haspermitted dose reduction, increased the availability and reduced cost ofthe vaccine. Therefore, it has been speculated that an adjuvantedvaccine formulation of sIPV would reduce cost and also increase thenumber of available sIPV doses worldwide.

Globally different research groups have been evaluating dose sparing forvaccines (Influenza vaccines in particular) by employing severaladjuvants namely Alum, Emulsion, TLR-agonists (MPL, CpG, poly-IC,imiquimod), dmLT, 1,25-dihydroxyvitamin D3, CAF01, poly [di(carboxylatophenoxy)-phosphazene] (PCPP) and Venezuelan equineencephalitis (VEE) replicon particles. Most of the adjuvant types beingstudied have encountered following hurdles i) Unknown safety orclassified as toxic by regulatory agencies ii) having limitationsregards to route of administration iii) lacking manufacturingreproducibility iv) stability of adjuvant.

Emulsion adjuvants (MF-59, AS03, AF3) have been previously reported toprovide a strong dose-reduction effect (>30 fold) for Influenza andHepatitis B vaccines. These adjuvants work by forming a depot at thesite of injection, enabling the meted release of antigenic material andthe stimulation of antibody producing plasma cells. However, theseadjuvants have been deemed too toxic for widespread human prophylacticvaccine use and are usually reserved for those severe and/or terminalconditions such as cancer where there is a higher tolerance ofside-effects.

Further, Aluminum salts have been considered safe, are already beingused in combination vaccines containing sIPV, have the lowestdevelopment hurdles and are inexpensive to manufacture. Howeveraluminium adjuvants are not known for permitting significantdose-reduction.

One of the most critical steps in the production of vaccines againstpathogens, in particular viral vaccines, is viral inactivation. In thecase of virus inactivation, formalin is the most frequently usedinactivating agent in the manufacture of vaccines. Formaldehydeinactivates a virus by irreversibly cross-linking primary amine groupsin surface proteins with other nearby nitrogen atoms in protein or DNAthrough a —CH2-linkage. A potential problem with using formalin forviral inactivation is that this involves a series of chemical reactionsthat produce reactive products that can induce cross-linking of viralproteins and aggregation of virus particles. This could hamper theinactivating efficiency of the formalin and could also result in thepartial destruction of the immunogenicity of the antigen in vaccine.Accordingly, it has been reported previously that formalin inactivationof polioviruses could affect the viral immunogenicity as well asantigenicity. Refer Morag Ferguson et al Journal of General Virology(1993), 74, 685-690. Most importantly, previously disclosed formaldehydeinactivation methods were particularly carried out in presence ofphosphate buffer wherein significant D-antigen losses were observedalong with epitope modification for Sabin Type I/II/III (D-antigenrecovery post inactivation: 22% for sabin type I, 15% for sabin type II,25% for sabin type III), thereby failing to preserve the epitopicconformation. It is therefore possible that antibodies produced byrecipients of formalin-inactivated polioviruses (in presence ofphosphate buffer) may not contribute to the protective immune response.

By combining formalin and UV-inactivation, scientists tried to overcomethe limitations of isolated UV-inactivation or formalin-inactivation,respectively, when inactivating the particularly resilient poliovirus.See, e.g., McLean, et al., “Experiences in the Production of PoliovirusVaccines,” Prog. Med. Virol., vol 1, pp. 122-164 (1958.) Taylor et al.(J. Immunol. (1957) 79:265-75) describe the inactivation ofpoliomyelitis virus with a formalin and ultraviolet combination. Molneret al. (Am. J. Pub. Health (1958) 48:590-8) describe the formation of ameasurable level of circulating antibodies in the blood of subjectsvaccinated with ultraviolet-formalin inactivated poliomyelitis vaccine.Truffelli et al. (Appl. Microbiol. (1967) 15:516-27) report on theinactivation of Adenovirus and Simian Virus 40 Tumorigenicty in hamstersby a three stage inactivation process consisting of formalin, UV lightand β-propiolactone (BPL). Miyamae (Microbiol. Immunol. (1986)30:213-23) describes the preparation of immunogens of Sendai virus by atreatment with UV rays and formalin. However previously discussedpromising alternatives for formaldehyde like β-propiolactone (BPL) havebeen reported to produce an immune complex-reaction when combined withother components of the rabies vaccine. Additionally, it has been shownto produce squamous cell carcinomas, lymphomas and hepatomas in mice.

It is therefore particularly desirable to employ favorable formaldehydeinactivation conditions that maintain the structural integrity ofantigenic structures of Sabin strains as well as utilize safe andcost-effective adjuvants that can result in significantly dose reduced(i.e. 8 to 10 fold) sIPV (Sabin IPV) vaccine compositions therebyreducing cost of manufacture, increasing vaccine supplies and makingvaccines affordable for developing countries.

The present inventors have surprisingly found that D-antigen lossespost-formaldehyde inactivation could be due to presence of phosphatebuffer that unexpectedly causes undesirable aggregation of polioviruses. The instant invention provides an improved process offormaldehyde inactivation in presence of TRIS buffer thereby ensuringminimal epitopic modifications and subsequently minimizing D-antigenlosses. Subsequently significantly dose reduced Sabin IPV vaccinecompositions with atleast 8 fold dose reduction for Sabin Type I and 3fold dose reduction for Sabin Type III can be obtained.

DESCRIPTION OF FIGURES

FIG. 1: Alum phosphate gel prepared in 0.9% NaCl (pH Vs Zeta potentialat different concentrations of Alum phosphate gel)

FIG. 2: Alum phosphate gel prepared in WFI (pH Vs Zeta potential atdifferent concentrations of Alum phosphate gel)

FIG. 3: Alum Hydroxide gel prepared in 0.9% NaCl (pH Vs Zeta potentialat different concentrations of Alum hydroxide gel)

FIG. 4: Alum Hydroxide gel prepared in WFI (pH Vs Zeta potential atdifferent concentrations of Alum hydroxide gel)

DETAILED DESCRIPTION

An important aspect of the instant invention is that said improvedprocess of formalin inactivation and adsorption on alum salt comprisesof following steps:

-   a) Adding Sabin IPV purified bulk to TRIS buffer (30 to 50 mM)    having pH between 6.8 to 7.2,-   b) Adding M-199 medium containing glycine (5 gm/1) to mixture of    (a),-   c) Adding 0.025% formaldehyde while mixing,-   d) Incubating mixture obtained in Step (c) at 37° C. from 5 to 13    days on magnetic stirrer,-   e) Subjecting post-incubation mixture to intermediate 0.22μ    filtration on day 7 and final filtration on day 13,-   f) Storing bulk obtained after step (e) at 2-8° C.,-   g) Performing D-Ag ELISA for D-Antigen unit determination,-   h) Taking the desired volume of autoclaved Al(OH)₃ to get the final    concentration of Alum(Al++) between 0.8 to 1.2 mg/dose in a 50 ml    Container,-   i) Adding sIPV bulk with adjusted D-Ag unit and making up the volume    with diluent (10×M-199+0.5 Glycine %),-   j) Adjusting the final formulation pH and obtaining final    formulation with pH between 6 and 6.5,-   k) Subjecting the formulation bulk to magnetic stirring overnight at    2-8° C. and wherein formalin inactivation of step (a) does not occur    in presence of phosphate buffer

A first embodiment of instant invention is that said buffer to be usedduring formaldehyde inactivation can be selected from the groupconsisting of TRIS, TBS, MOPS, HEPES, and bicarbonate buffers.

A preferred aspect of first embodiment is that said formaldehydeinactivation can occur in presence of TRIS Buffer or TBS (TRIS Bufferedsaline) having concentration selected from 30 mM, 40 mM and 50 mM,preferably 40 mM and at a pH selected from 6.8, 6.9, 7, 7.1 and 7.2,preferably between 6.8 and 7.2 wherein said inactivation does notutilize any phosphate buffer.

A second embodiment of the instant invention is that adsorption offormalin inactivated sIPV can be done on aluminium hydroxide havingconcentration selected from 1.5 mg/dose, 1.8 mg/dose, 2.2 mg/dose,preferably between 2 mg/dose to 2.4 mg/dose and at a pH selected from6.2, 6.3, 6.4 and 6.5, preferably 6.5.

A third embodiment of instant invention is that said improved process offormalin inactivation and aluminium hydroxide adsorption can result inD-Antigen recovery post-inactivation between 50% and 80% and percentadsorption of aluminium hydroxide can be between 85 and 99%.

One aspect of third embodiment is that present invention provides animproved process of formalin inactivation and aluminium hydroxideadsorption resulting in dose reduction of atleast 8 fold for Sabin TypeI, atleast 3 fold for Sabin Type III as compared to standard dose of 40DU-8DU-32DU. Second aspect of third embodiment is that instant inventionprovides improved formaldehyde inactivation and aluminium hydroxideadsorption methods that result in vaccine compositions comprising of i)inactivated poliovirus type 1 at a dose of atleast 5D-antigen units, ii)inactivated poliovirus type 2 at a dose of atleast 8D-antigen units andiii) inactivated poliovirus type 3 at a dose of atleast 10D-antigenunits.

A fourth embodiment of instant invention is that said aluminium saltadjuvant is an aluminium hydroxide having concentration between 1.5mg/0.5 ml dose and 2.5 mg/0.5 ml dose, preferably between 2.100 mg/0.5ml dose and 2.4 mg/0.5 ml dose at a pH of about 6.5.

One aspect of fourth embodiment is that total aluminium content in thetrivalent vaccine (Type 1, 2 and 3) can be between 800-1000 μg,preferably 800 μg Al³⁺+ per 0.5 mL dose, characterized in that atleast400 μg Al³⁺ for Type 1, atleast 200 μg Al³⁺ for Type 2, atleast 200 μgAl³⁺ for Type 3.

Another aspect of fourth embodiment is that said dose reduced poliovirus vaccine composition can consist of Type 1 and Type 3 and is devoidof Type 2 wherein the dose volume can be between 0.1 and 0.4 ml.

The dose reduced vaccine compositions prepared by instant methods can bei) “Standalone sIPV” wherein the antigens may comprise of sIPV type 1 orsIPV type 2 or sIPV type 3, or sIPV types 1 and 2, or sIPV types 1 and3, or sIPV types 2 and 3, or sIPV types 1, 2 and 3 or ii) “CombinationVaccines containing sIPV” wherein said non-IPV antigens of combinationvaccines can be selected from but not limited to diphtheria toxoid,tetanus toxoid, whole cell pertussis antigen(s), acellular pertussisantigen(s), Hepatitis B surface antigen, Haemophilus influenzae bantigen(s), Neisseria meningitidis A antigen(s), Neisseria meningitidisC antigen(s), Neisseria meningitidis W-135 antigen(s), Neisseriameningitidis Y antigen(s), Neisseria meningitidis X antigen(s),Neisseria meningitidis B bleb or purified antigen(s), Hepatitis Aantigen(s), Salmonella typhi antigen(s), Streptococcus pneumoniaeantigen(s).

The non-IPV antigen(s) may be adsorbed onto an aluminium salt such asaluminium hydroxide, an aluminium salt such as aluminium phosphate oronto a mixture of both aluminium hydroxide and aluminium phosphate, ormay be unadsorbed.

Poliovirus may be grown in cell culture. The cell culture may be a VEROcell line or PMKC, which is a continuous cell line derived from monkeykidney. VERO cells can conveniently be cultured microcarriers. Aftergrowth, virions may be purified using techniques such asultrafiltration, diafiltration, and chromatography. Prior toadministration to patients, the viruses must be inactivated, and thiscan be achieved by treatment with formaldehyde.

Compositions may be presented in vials, or they may be presented inready filled syringes. The syringes may be supplied with or withoutneedles. A syringe will include a single dose of the composition,whereas a vial may include a single dose or multiple doses (e.g. 2doses). In one embodiment the dose is for human. In a further embodimentthe dose is for an adult, adolescent, toddler, infant or less than oneyear old human and may be administered by injection.

Vaccines of the invention may be packaged in unit dose form or inmultiple dose form (e.g. 2 doses). The said multidose composition can beselected from a group consisting of 2 dose, 5 dose and 10 dose. Formultiple dose forms, vials are preferred to pre-filled syringes.Effective dosage volumes can be routinely established, but a typicalhuman dose of the composition for injection has a volume of 0.5 mL.

EXAMPLES Example 1

Purification of Sabin IPV (sIPV)

1) Tangential Flow Filtration (TFF):

-   -   Clarified harvest pool was concentrated to 10× using tangential        flow filtration system with 100 Kda cassettes (0.5 m²) and then        diafiltered 3 times of harvest volume with phosphate buffer (40        mM, pH: 7.0)

2) Column Chromatography:

-   -   The purification was done by Ion Exchange Chromatography (IEC).        10×TFF concentrate was passed through DEAE Sepharose fast flow        (Weak-Anion exchanger) packed in column xk-26 using Akta        explorer (GE Healthcare). Negatively charged impurities was        found to bind to the column whereas polio virus was collected in        flow through with phosphate buffer 40 mM.

3) TRIS Buffer Exchange:

-   -   To minimize the loss of antigen in a quite cumbersome        inactivation procedure (13 days), purified virus pool was buffer        exchanged from phosphate buffer to TRIS buffer (40 mM, pH: 7)        with TFF system (100 KDa, 0.1 m2). The purified virus pool was        exchanged with three volumes of tris buffer.

Example 2

A) Inactivation of sIPV

-   -   10× concentrated M-199 with 0.5% glycine was added so as to        achieve final concentration 1×. Inactivation agent formalin        (0.025%) was added into purified virus bulk while constant        mixing. Inactivation was carried out at 37° C. while continuous        stirring for 13 days containing 0.22 u filtration on 7th day and        13th day.

B) Inactivation of sIPV in TRIS Buffer and Phosphate Buffer

0.025% formaldehyde was used for inactivation for 13 days at 37° C.

TABLE 1 D-Antigen Content, Formalin inactivation in presence of TRISbuffer and Phosphate buffer D-Antigen content (40 mM D-Antigen content(40 mM Phosphate buffer during Tris buffer during Inactivation)Inactivation) Type 1 52.70 DU/ml 408.19 DU/ml Type 2 22.63 180.20 Type 34.21 21.50

When formaldehyde inactivation methods were particularly carried out inpresence of phosphate buffer, significant D-antigen losses were observedfor Sabin Type I. Whereas it was found that formaldehyde inactivation inpresence of TRIS buffer resulted in minimum loss of D-antigen.

TABLE 2 Different concentrations of TRIS Buffer used during inactivation30 mM 40 mM 50 mM Type 1 500 DU/ml 576.80 DU/ml 585 DU/ml Type 2 140DU/ml 165.16 DU/ml 155 DU/ml Type 3  16 DU/ml  21.17 DU/ml  19 DU/ml

-   -   TRIS Buffer at a concentration of 40 mM was found to be most        efficient in terms of D-Antigen content preservation for sIPV 1,        2 and 3.

C) D-Antigen Content Determination by ELISA.

Day 1: Plate Coating:

-   -   1. 100 ul of specific bovine anti polio was pippeted in PBS per        well    -   2. Microtiter plate was sealed and incubated overnight at room        temperature.

Day 2: Blocking:

-   -   1. The plates were washed (Washing/dilution buffer −0.05% tween        20 in 1×PBS) 3 times.    -   2. 300 ul block buffer (1% BSA in PBS) was pipetted per well.    -   3. The plate was sealed and incubated for 45 minutes at 37±1° C.

Sample Addition:

-   -   1. The plate was washed 3 times.    -   2. 100 ul of sample diluent was added in all wells except well        of row A.    -   3. 100 ul standard was added to first two wells of column 2 and        3.    -   4. 100 ul sample was added to first two wells of column 4-12.    -   5. Prediluting sample to a suitable concentration.    -   6. 100 ul sample diluents was added to first two wells of column        1.    -   7. Serial two fold dilution were made down the column by        transferring 100 ul from each well to adjacent well of the same        column and discarding 100 ul from the last well.    -   8. Incubating at 37° C. for 2 hr.    -   9. Plates were kept overnight at 4° C.

Day 3: Monoclonal Antibody Addition:

-   -   1. The plate was washed 3 times.    -   2. 100 ul diluted (1:240) type specific monoclonal antibodies        were added.    -   3. The plates were sealed and incubated for 2 hours at 37° C.

Conjugate:

-   -   1. The plate were washed 3 times    -   2. 100 ul diluted conjugate (Type1-1:2400, Type2-1:1500,        Type3-1:4800) was added.    -   3. The plate was sealed and incubated for 1 hour at 37° C.

Substrate Addition:

-   -   1. 100 ul TMB substrate was added to all wells.    -   2. Mixture incubated at room temperature for 10 minutes.    -   3. Reaction was stopped by adding 100 ul 2M H2SO4.    -   4. Plate was read at 450/630 nm.    -   5. D antigen concentration was calculated using KC4 software.

Example 3

Adsorption of sIPV:

-   -   1. Autoclaved 1% stock of Al(OH)₃ and AlPO₄ was used for the        preparation of formulations.    -   2. Desired volume of Al(OH)₃/AlPO₄ was taken to get the required        concentration of alum in a 100 ml glass bottle.    -   3. Inactivated polio virus bulk with known D-Ag Unit was added        and volume make up was done with diluent.    -   4. Final formulation pH was adjusted to 6.5 with 1 N HCl/NaOH.    -   5. The formulation bulk was kept on magnetic stirrer overnight        at 2-8° C.

Example 4

Preformulation Studies

Different concentrations of Al(OH)₃ & AlPO₄ were prepared in 0.9% salineand in WFI to check size and zeta potential with respect to change inpH.

It was observed that zeta potential of AlPO₄ decreases (negativity) withincrease in pH from 5 to 7.5 in presence of WFI as well as in saline(Refer FIGS. 1 and 2).

Whereas, zeta potential of Al(OH)₃ in saline remains constant,independent of pH and Al(OH)₃ salt concentration (Refer FIGS. 3 and 4).

Example 5

Adsorption Studies of sIPV on Alum Phosphate and Alum Hydroxide

TABLE 3 Sabin Type 1, 2&3 (Titer 10^(6.0)/dose) adsorption on alum (Alumphosphate and Alum Hydroxide) Virus Titer (per Particles % free in %adsorbed Sample does) (in K) SUP on gel Type 1, Control 5.45 284 NAAlOH₃ Al+++ 4.15 14 4.98 95.02 125 ug/dose Al+++ 3.85 7 2.49 97.51 250ug/dose Al+++ 3.8 6.3 2.24 97.78 500 ug/dose Type 1, Control 5.84 691 NAAlPO₄ Al+++ 3.49 3 0.43 99.57 125 ug/dose Al+++ 3.09 1.2 0.17 99.83 250ug/dose Al+++ 2.94 0.87 0.12 99.87 500 ug/dose Type 2, Control 5.49 309NA AlOH₃ Al+++ 3.59 3.89 1.25 98.75 125 ug/dose Al+++ 3.49 3.09 1 99 250ug/dose Al+++ 3.49 3.09 1 99 500 ug/dose Type 2, Control 5.49 309 NAAlPO₄ Al+++ 3.15 1.41 0.45 99.5 125 ug/dose Al+++ 3.09 1.23 0.39 99.6250 ug/dose Al+++ 3.09 1.23 0.39 99.6 500 ug/dose Type 3, Control 5.59389 NA AlOH₃ Al+++ 4.14 13.8 3.54 96.47 125 ug/dose Al+++ 3.94 8.7 2.2397.77 250 ug/dose Al+++ 3.54 3.4 0.87 99.13 500 ug/dose Type 3, Control5.59 389 NA AlPO₄ Al+++ 5.34 218 56.04 43.96 125 ug/dose Al+++ 5.24 17344.47 55.53 250 ug/dose Al+++ 5.16 144 37.01 62.9 500 ug/dose

It was found that Sabin polio virus type-3 shows only 50-60% adsorptionwith aluminium phosphate (AlPO₄). Whereas, Sabin polio virus type-3shows atleast 90% adsorption with Al(OH)₃. Thus, Alum hydroxide wasfound to be more efficient as compared to Alum phosphate with respect toadsorption of Sabin Type 1, 2 and 3.

Example 6

Immunogenicity Studies of Alum Adsorbed sIPV

To check immune response of adjuvanted sIPV in rat (Sera NeutralisationTest) SNT test was carried out. Sera was separated and used to test thepresence of neutralizing antibodies for type specific polio virus.Control sera used to validate the test. Virus back-titration was alsoperformed to get the number of challenge virus particles added.

Animal Model: Wistar rat (8 weeks, approx 200 gm) 50% male and 50%female per group.

Route of Inoculation: Intra Muscular.

Volume: 0.5 ml

Blood withdrawal: on day 21.

Site of bleeding: Retro-Orbital plexus.

TABLE 4 Type 1 Group 1 Group 2 Group 3 Group 4 Group 5 Group 6 Group 7Group 15 Comm. 5 DU 2.5 DU 1 DU 5 DU 2.5 DU 1 DU −ve IPV 1.15 mgOH 1.15mgOH 1.15 mgOH 1.8 mgPO4 1.8 mgPO4 1.8 mgPO control Rat SNT Sera SeraSera Sera Sera SNT Sera Sera Sera No +ve Titer SNT Titer SNT Titer SNTTiter SNT Titer +ve Titer SNT Titer SNT Titer 1 1 (1:2) 8 (1:256) 1(1:2) 4  (1:16) 5 (1:32) 5 (1:32) 2 (1:4) 0 (<1:2) 2 1 (1:2) 5 (1:32)  1(1:2) 7  (1:128) 8  (1:256) 4 (1:16) 1 (1:2) 0 (<1:2) 3 0 (<1:2)  7(1:128) 3 (1:8) 0 (<1:2)  4 (1:16) 6 (1:64) 0 (<1:2)  0 (<1:2) 4 0(<1:2)  11  (1:2048) 2 (1:4) 2 (1:4) 1 (1:2)  5 (1:32) 0 (<1:2)  0(<1:2) 5 7  (1:128) 3 (1:8)  7  (1:128) 5  (1:32) 6 (1:64) 4 (1:16) 1(1:2) 0 (<1:2) 6 4  (1:16) 7 (1:128)  7  (1:128) 1 (1:2) 5 (1:32) 6(1:64) 3 (1:8) 0 (<1:2) 7 3 (1:8) 5 (1:32)  4  (1:16) 1 (1:2) 8  (1:256)7  (1:128) 0 (<1:2)  0 (<1:2) 8 1 (1:2) 7 (1:128) 3 (1:8) 2 (1:4) 6(1:64) 0 (<1:2)  0 (<1:2)  0 (<1:2) 9 3 (1:8) 8 (1:256)  2 (1:4) 3 (1:8)8  (1:256) 4 (1:16) 4  (1:16) 0 (<1:2) 10 3 (1:8) 7 (1:128) 4  (1:16) 5 (1:32) 6 (1:64) 2 (1:4)  2 (1:4) 0 (<1:2)

It was surprisingly found that Alum hydroxide adjuvanted Type 1 SabinIPV having 5 DU/dose gave better seroconversion as compared to Salk IPVvaccine with 40 DU/dose and Alum phosphate adjuvanted Sabin IPV having 5DU/dose.

TABLE 5 Type 2 Group 1 Group 2 Group 3 Al(OH)3 Adjuvanted 4 DU( 0.6mgOH) 8 DU( 0.6 mgOH) 16 DU 0.6 mgOH Rat Sera Sera Sera No SNT +ve TiterSNT +ve Titer SNT +ve Titer 1 3 (1:8)  4 (1:16) 7 (1:128) 2 4 (1:16) 6(1:64) 5 (1:32)  3 0 (<1:2)  3 (1:8)  5 (1:32)  4 3 (1:8)  4 (1:16) 6(1:64)  5 5 (1:32) 7  (1:128) 6 (1:64)  6 6 (1:64) 4 (1:16) 9 (1:512) 74 (1:16) 7  (1:128) 4 (1:16)  8 5 (1:32) 3 (1:8)  8 (1:256) 9 7  (1:128)8  (1:256) 8 (1:256) 10 5 (1:32) 3 (1:8)  8 (1:256)

Type 2 sIPV having 8 DU/dose with adjuvant gave equivalent seroconversion as compared to Salk IPV vaccine with 8 DU/dose.

TABLE 6 Type 3 Group 1 Group 2 Group 3 Al(OH)3 Adjuvanted 10 DU 0.6 mgOH5 DU 0.6 mgOH 2.5 DU 0.6 mgOH Rat Sera Sera Sera No SNT +ve Titer SNT+ve Titer SNT +ve Titer 1 3 (1:8)  2 (1:4) 0 (<1:2)  2 0 (<1:2)  5 (1:32) 1 (1:2) 3 2 (1:4)  3 (1:8) 1 (1:2) 4 4 (1:16) 2 (1:4) 0 (<1:2) 5 4 (1:16) 2 (1:4) 1 (1:2) 6 4 (1:16) 1 (1:2) 1 (1:2) 7 9  (1:512) 0(<1:2)  2 (1:4) 8 7  (1:128) 2 (1:4) 2 (1:4) 9 1 (1:2)  0 (<1:2)  1(1:2) 10 5 (1:32) 7   (1:128 1 (1:2)

It was found that Type 3 sIPV having 10 DU/dose with adjuvant gaveequivalent sero conversion as compared to Salk IPV vaccine with 32DU/dose.

TABLE 7 Maximum dose reduction observed for individual Sabin Type 1, 2 &3 after studies. sIPV Standard dose *SIIL Dose Dose reduction Type 1 40DU 5 DU ~8 Folds Type 2  8 DU 8 DU Equivalent Type 3 32 DU 10 DU  ~3Folds

SIIL: Serum Institute of India In House dose reduced IPV preparation.

In view of the many possible embodiments to which the principles of thedisclosed invention may be applied, it should be recognized that theillustrated embodiments are only preferred examples of the invention andshould not be taken as limiting the scope of the invention. Rather, thescope of the invention is defined by the following claims. We thereforeclaim as our invention all that comes within the scope and spirit ofthese claims.

1. A method for producing a composition comprising Enteroviralparticles, wherein the method comprises the steps of: a) producing amedium containing the Enteroviral particles; b) purification of theEnteroviral particles from the medium; c) stabilization of purifiedEnteroviral particles; d) formalin inactivation of the Enteroviralparticles whereby during at least a part of the inactivation a bufferother than a phosphate buffer is present at a concentration sufficientto prevent or reduce aggregation of the Enteroviral particles therebyreducing the D-antigen losses post inactivation by 8 to 10 fold ascompared to phosphate buffer; and e) adsorption of Enteroviral particleson aluminum salt adjuvant whereby percentage adsorption on alum isatleast 95%.
 2. The method according to claim 1, wherein the buffer ofstep (d) is selected from the group consisting of TRIS, TBS, MOPS, HEPESand bicarbonate buffers.
 3. The method according to claim 2, wherein thebuffer is a TRIS buffer having a pH of about 6.8 to 7.2 and at aconcentration in the range of 30 mM-70 mM, preferably 40 mM.
 4. Themethod according to claim 1, wherein the aluminum salt adjuvant of step(e) is selected from a group of aluminum hydroxide, or aluminumphosphate, or a mixture of both.
 5. The method according to claim 4,wherein the aluminum salt adjuvant is an aluminum hydroxide havingconcentration between 1.5 mg/0.5 ml dose and 2.5 mg/0.5 ml dose,preferably between 2.100 mg/0.5 ml dose and 2.4 mg/0.5 ml dose at a pHof about 6.5.
 6. The method according to claim 5, wherein total aluminumcontent in the trivalent vaccine is 0.8-1.2 mg, preferably 0.8 mg Al³⁺per 0.5 mL dose, characterized in that atleast 0.4 mg Al³⁺ for Type 1,atleast 0.2 mg Al³⁺ for Type 2, atleast 0.2 mg Al³⁺ for Type
 3. 7. Themethod according to claim 1, wherein the composition comprisingEnteroviral particles is a vaccine.
 8. The method according to claim 7,wherein the Enteroviral particles are of an Enterovirus of polioviruses.9. A The method according to claim 8, wherein the Enteroviral particlescomprise polioviruses of the Sabin serotypes 1, 2 and
 3. 10. The methodaccording to claim 8, wherein the Enteroviral particles comprisepolioviruses of Salk serotypes IPV type 1 (Mahoney strain), IPV type 2(MEF-1 strain); and/or IPV type 3 (Saukett strain).
 11. The methodaccording to claim 7, wherein the vaccine is a dose reduced InactivatedPolio Vaccine (IPV).
 12. The method according to claim 11, wherein thedose reduced Inactivated Polio vaccine comprises: i) inactivatedpoliovirus type 1 at a dose less than 15 D-antigen units instead ofstandard dose of 42 DU; and/or ii) inactivated poliovirus type 2 at adose less than 18 D-antigen units; and/or iii) inactivated poliovirustype 3 at a dose less than 15 D-antigen units instead of standard doseof 32 DU.
 13. The method according to claim 15, wherein the method forpreparing the dose reduced inactivated Polio vaccine containing Salk orSabin polioviruses comprises the steps of: a) producing a mediumcontaining the polioviruses; b) purification of the polio viruses fromthe medium; c) stabilization of purified polioviruses by addition ofM-199 medium containing glycine; d) inactivation of the polio viruses byusing formaldehyde 0.025% at 37° C. for 5 to 13 days in presence of TRISbuffer at a concentration between 30 mM to 60 mM to prevent or reduceaggregation of the poliovirus particles thereby reducing the D-antigenlosses post inactivation by 8 to 10 fold as compared to phosphatebuffer; and e) adsorption of inactivated polioviruses on Alum hydroxideadjuvant having concentration between 2 to 2.5 mg/dose, wherebypercentage adsorption on Alum hydroxide is greater than 95% for Type 1,Type 2 and Type
 3. 14. The method according to claim 15, wherein themethod for preparing the dose reduced inactivated Polio vaccinecontaining Salk or Sabin polioviruses comprises the steps of: a)producing a medium containing the polioviruses; b) purification of thepolio viruses from the medium; c) stabilization of purified poliovirusesby addition of M-199 medium containing glycine; d) inactivation of thepolio viruses by using formaldehyde 0.025% at 37° C. for 5 to 13 days inpresence of TRIS buffer at a concentration between 30 mM to 60 mM toprevent or reduce aggregation of the poliovirus particles therebyreducing the D-antigen losses post inactivation by 8 to 10 fold ascompared to phosphate buffer; and e) adsorption of inactivatedpolioviruses on Alum hydroxide adjuvant having concentration between 2to 2.5 mg/dose, whereby percentage adsorption on Alum hydroxide isgreater than 95% for Type 1 and Type
 3. 15. The method according toclaim 11, wherein the dose reduced Inactivated Polio vaccine can beselected from a group of: i) Sabin single dose composition having SabinType 1, Type 2, Type 3 combination selected from 5-16-10; ii) Sabin twodose composition having Sabin Type 1, Type 2, Type 3 combinationselected from 5-16-10; iii) Sabin single dose composition having SabinType 1, Type 2, Type 3 combination selected from 2.5-8-5; iv) Sabin twodose composition having Sabin Type 1, Type 2, Type 3 combinationselected from 2.5-8-5; v) Sabin single dose composition having SabinType 1, Type 2, Type 3 combination selected from 5-8-10; vi) Sabin twodose composition having Sabin Type 1, Type 2, Type 3 combinationselected from 5-8-10; vii) Salk single dose composition having SabinType 1, Type 2, Type 3 combination selected from 7.5-16-10; viii) Salktwo dose composition having Sabin Type 1, Type 2, Type 3 combinationselected from 7.5-16-10; ix) Salk single dose composition having SalkType 1, Type 2, Type 3 combination selected from 8-2-5; x) Salk two dosecomposition having Salk Type 1, Type 2, Type 3 combination selected from8-2-5; xi) Salk single dose composition having Salk Type 1, Type 2, Type3 combination selected from 10-2-5; xii) Salk two dose compositionhaving Salk Type 1, Type 2, Type 3 combination selected from 10-2-5;xiii) Salk single dose composition having Salk Type 1, Type 2, Type 3combination selected from 10-2-12; xiv) Salk two dose composition havingSalk Type 1, Type 2, Type 3 combination selected from 10-2-12; xv) Salksingle dose composition having Salk Type 1, Type 2, Type 3 combinationselected from 5-2-5; and xvi) Salk two dose composition having Salk Type1, Type 2, Type 3 combination selected from 5-2-5.
 16. The methodaccording to claim 15, wherein the dose reduced Salk or SabinInactivated Polio Vaccine does not comprise Type
 2. 17. The methodaccording to claim 15, wherein a multivalent vaccine consisting of dosereduced IPV can comprise of one or more antigens from a pathogenselected from a list consisting of: Haemophilus influenzae b, Neisseriameningitidis type A, Neisseria Meningitidis type C, Neisseriameningitidis type W, Neisseria meningitidis type Y, Neisseriameningitidis type X, Neisseria meningitidis type B, Streptococcuspneumoniae, Streptococcus agalactiae Salmonella typhi, Hepatitis A,Hepatitis B, RSV, Hepatitis C, diphtheria toxoid, tetanus toxoid, wholecell pertussis, acellular pertussis, Staphylococcus aureus, anthrax,Vibrio cholera, Zika, Ebola, Chikungunya, dengue, malaria, measles,mumps, rubella, BCG, Japanese encephalitis, Rotavirus, smallpox,Shigella, yellow fever, typhoid, CMV, Shingles, Varicella virus, HPV,HSV, and HIV.